The invention relates generally to the field of electrical components and more particularly to the structural design of vacuum-type interrupters, whose housings are comprised of two cap-like metal parts and of an annular insulator and whose intended purpose, therefore, is for switching in a low-voltage range.
In the case of a known vacuum-type interrupter, which is used as a protective tube and, thus, for switching currents on the order of magnitude of 1 to 2 kA for voltages of up to about 1000 V, the housing enveloping the stationary contact and the contact that is axially movable thereto is comprised of two cap-like metal parts and of an annular insulator, to which the two cap-like metal parts are hermetically sealed by means of a knife-edge soldered joint. The stationary and the movable contact member, a cylindrical shield covering the annular insulator, and the bellows associated with the movable contact stud are disposed axially one behind the other inside the housing. The bellows is brazed with its one end to the supporting disk connected to the movable contact stud (EP 0 254 089 A1).
In the case of another known vacuum-type interrupter for the low voltage range, no cylindrical shielding is provided, but rather a cap-like protective shield that opens toward the bellows. In this case, the annular insulator, whose wall thickness is nearly equal to its axial length, is disposed concentrically to the bellows (EP 0 054 670 A2).
In the case of other vacuum-type interrupters used in the middle voltage range, it is likewise known to arrange a cap-shaped protective shield between the contact member and its rear space, in particular also between the movable contact member and the bellows associated with the movable contact, this protective shield protecting the bellows and, in some instances, an associated hollow cylindrical or disk-shaped insulating part from the condensing of vaporized electrode material (U.S. Pat. Nos. 3,674,958; 3,996,437; 4,417,110).
Another vacuum type interrupter switches d.c. currents up to about 6 kA given a d.c. voltage of up to 10 V. in that case one or both contacts have assigned to them a cap-like protective shield, which opens toward and projects over the arc gap and which shields the hollow cylindrical insulator disposed concentrically to the arc gap (U.S. Pat. No. 4,216,360 A1).